In 1943, Pope Pius XII wrote: “As you well know, venerable brethren, it is true that venial sins may be expiated in many ways that are to be highly commended. But to ensure more rapid progress day by day in the path of virtue, we will that the pious practice of frequent confession, which was introduced into the Church by the inspiration of the Holy Spirit, should be earnestly advocated. By it genuine self-knowledge is increased, Christian humility grows, bad habits are corrected, spiritual neglect and tepidity are resisted, the conscience is purified, the will strengthened, a salutary self-control is attained, and grace is increased in virtue of the sacrament itself” (Mystici Corporis 88).
The confessing of venial sins is “strongly recommended” by the Catechism of the Catholic Church (cf. CCC 1458).